Assuming that the addition concentration is 0.2mol/L, after equal volume mixing, their concentrations are all 0.1mol/L.

The concentration of hydrogen ions in the solution is c(H? )=√cKa = √( cKw/Kb)= √( 0. 10× 1.0× 10？ / 1.8× 10? )=7.5× 10?

pH=-lg7.5× 10？ =5. 1

Extended data:

Prevention and control of hazards of hydrochloric acid;

1, operation matters.

When using hydrochloric acid, you should cooperate with personal protective equipment. Such as rubber gloves or PVC gloves, goggles, chemical-resistant clothes and shoes. To reduce the danger caused by direct contact with hydrochloric acid. Closed operation, pay attention to ventilation. The operation should be as mechanized and automated as possible. Operators must be specially trained and strictly abide by the operating procedures.

It is recommended that operators wear self-priming filter gas mask (full face mask), rubber acid and alkali resistant clothing and rubber acid alkali resistant gloves. Keep away from flammable and combustible materials. Prevent the steam in the workplace from leaking into the air. Avoid contact with alkali, amine and alkali metals. When handling, handle with care to prevent the packaging and containers from being damaged. Equipped with leakage emergency treatment equipment. Empty containers may leave harmful substances behind.

2, acid mist treatment

In the process of using hydrochloric acid, a large amount of hydrogen chloride gas will be produced. The suction device can be installed on the container side, and then the hydrochloric acid mist can be discharged to the outdoor for treatment with the help of fans, acid mist purifiers, air pipes and other equipment and facilities. Acid mist inhibitor can also be added to hydrochloric acid to inhibit the volatilization of acid mist of hydrochloric acid.

3. Emergency treatment of leakage

Emergency treatment: quickly evacuate the personnel in the leaked and polluted area to a safe area, isolate them, and strictly restrict access. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and acid-proof overalls. Don't touch the leak directly. Cut off the leakage source as much as possible.

Small amount of leakage: mixed with sand, dry lime or soda ash. It can also be washed with plenty of water, diluted with clear water and put into the wastewater system.

A large number of leaks: damming or digging holes to contain them. Pump it into a tank car or a special collector with a pump, and recycle it or transport it to a waste disposal site for treatment.

4, fire control measures

Hazard characteristics: It can react with some active metal powders and release hydrogen. When cyanide is encountered, it can produce highly toxic hydrogen cyanide gas. Neutralization reaction with alkali, releasing a lot of heat. It is very corrosive.

Fire extinguishing method in the presence of hydrochloric acid: neutralize with alkaline substances such as sodium bicarbonate, sodium carbonate and hydrated lime. You can also fight with a lot of water.

5, first aid measures

Skin contact: Take off contaminated clothes immediately, rinse with plenty of flowing water for at least 15 minutes, and apply weakly alkaline substances (such as alkaline water and soapy water) for medical treatment.

Eye contact: lift the eyelid immediately and rinse it thoroughly with plenty of flowing water or normal saline for at least 15 minutes. See a doctor.

Inhalation: leave the scene quickly and go to a place with fresh air. Keep the respiratory tract unobstructed. If you have difficulty breathing, give oxygen. If breathing stops, give artificial respiration immediately. See a doctor.

Ingestion: rinse your mouth with plenty of water, swallow a lot of raw egg white or milk (baking soda and other drugs are prohibited), and seek medical advice.